Process for the electrolytic production of copper.



UNITED STATES PATENT orrron.

. JQHANNES ALBERT WILHELM BORCHERS, or AACHEN, PAUL RUDOLF FRANKE, OF EISLEBEN, AND FRANZ EMIL GITNTHER, or AAGHEN,

GERMANY.

enoczss FOR THE ELECTROLYTIC PRODUCTION OF COPPER- Specification of Letters Patent. arming and September 21,1905. Serial No. 219,504.

Patented Sept. 11,1906.

To all whom it may concern.-

' Electrolytic Production of Copper, of which the following is a specification.

The direct electrolytic treatment of copper matte is an old problem which, notwithstanding numerous experiments made both on a large and on a-small scale and in many in-. stances at considerable expenditure, has remained practically unsolved until the discovery of the principles constituting the basis of the present process. e reasons for the want of success and the means whereby the difliculties may be overcome were not determined prior to experimentscarried out by us.

In the experiments at Stolberg it was .discovered that in the electrolysis 1n acid solutions of copper sulfate, of the kinds of copper matte formerly employed by the cooperation of ferric sulfate, Fe (S0,),, or of SO ions from the 'sulfid's forming the anode mass sulfur was deposited on the surface of .the anode and the metals passed into the solution at first readily, but subse uently only with the oonsum tion of consi erable electromotive force t e co per was transferred from said anode onto t ecathode. Now we have discovered that the reasons for this are as follows: 0 overcome the afiinity between Cu,S and FeS and other sulfids re uires of itself a larger ex enditure of power than was allowed for in the calculations of revious experimenters. The amount per un1t of volume and the mechanical nature of the sulfur that is separated out of FeS (which is the metallic sulfid occurr' in greater part as a subsidi constituent 1n copper matte) and that of t he sulfur separated out of Cu,S are show:

1. FeS (88)::Fe (56) +s 32 2. 011,8 (158)=Cu. (12 6) +8 (32).

Thus for the same residual amount of sulfur there disappear in the process of solution fifty-six parts, by weight, of metal inthe first case,and one hundre' and twenty-six parts, by weight, of metal in. the second casethat is to say, one atom of metal in the first case-and materially different, as a glance at the values of the molecular and atomlc-weights w1ll 5o two atoms of metal in the second case." The greater the percentage of contained FeS the greater the quantity and the denser the nature of the sulfur that remains behind per unit of volume on the anode.

The greater the amount of sulfurand the more densely it is de osited the more rapidly does the mechanica resistance a 'ainstthe access of the active constituents of the electrolyte to the anode mass which is still to bedissolved increase. fore the products of electrolysis formed on the still active surface of the anode are able to pass away so much easier substances which give rise to disturbing or costly electromotlve counteractions are produced underneath the covering of sulfur which prevents the equalization of concentration. Naturally the amount and the chemical character of the foreign metals (which are still present in comparatively large quantities in matte poor in copper) play. a certain part in the formation of such disturbing compounds (peroxid of lead, for example;) but these drawbacks are obviated without special measures in carrying out the ascertained preliminary conditions (which we shall now proceed to describe) for the electrolytic treatment of copper matte.

We have discovered that the difficulties which have hitherto hindered the electrolysis of copper matte are removed by smelting the matte to a degree of concentration of approximately ci hty per cent. of copper by means The more slowly there mass into plates or other suitable shapes and of co per n this noted that a concentration electrolyzing the latter as anodes inan electrolyte composed of acidulated aqueous solution of sheets as cathodes.

- A concentration of seventy-eight per cent. but below.

is suflicient in practice; e ee of concentrationthe difliculties which have been'observed in the case of almostall earlier ex eriments with poorer matte increase in'suc a remarkable manner that a matte containin say, seventy-two per cent. of cop er mayie saidto be almost as unsuitable or electrolytic treatment as the matte containin fifteen to twenty per cent. of copper, Whic was formerly used at Stolberg.

It is not advisable to concentrate a matte to more than eighty per cent. ofcopper on account of the increasing'separation of copper during the concentrating process. In such case the o eration approaches the stages ofthe pro notion of crude or black copper, whereas the obiect of the present invention is to electro yze. copper matte. Consequently the limits of direct electrolytic treatment of copper matte, as determined by the present invention lie above seventy two per cent eighty per cent. of copperthat is to say at seventy-eight per cent. when it is desired to restrict the separation of bottom' copper as muchas possible in the concentration by smelting.

As is well known, the concentrationof copper matte can' be carried beyond ei hty per cent. 'of copper; but then separation 0 copper takes place in great quantities, so that in casting the concentrates into anodes there are obtained mixtures of co per sulfid and metallic separated copper an alloys of both, which naturally can also be electrolyzed. the matte does but itis to be beyond eighty per cent. of copper also increases the cost of production wit out obtaining any correspondingadvantages.

If .matte containing seventy-eight to eighty per cent. of copper be electrolyzed with a current density of about seventy-five amnot hinder the electrolysis;

-peres per .square meter of the cathode or anode surface,

remain generally the electrical ressure in the bath between the anode and the cathode will below 1.0 volt at ordinary tem erature and with customary circulation of t e' electrolyte even after'la "ers of sulfur of some thickness have been eposited.

Whether and 'hOW often the deposits of copper sulfate opposite to pure copper 'of copper to, say,

sulfur must be scraped off from the anode during the electrolysis will depend chieflyon the local conditions, especial of wages and cost of power. applicable rules can be laid down on these points. The sulfur crusts which are scralpued off from the anodes or which remain as al residuals may be utilized by first lixiviating the sulfur by means of its known solvents, or by melting it out, (for instance, according to Schaflner, by means of water .and steam ressure, described in Lun ge, Sodat'ndustrie, 2d Edition, Vol. 2, ages 733 and 735,) or by working it up into own sulfur compounds (for instance, sulfuric acid)by means of known methods. g

Any residue'left after removal of the sulfur by carrying out any of these processes which may contain undecomposed sulfids and other compounds of the original constituents of the matte, and even metals, (for instance, copper and the precious metals,)1s treated for the recovery of copper vitriol and the precious metals, as .the case may be, like the anode mud of copper-refinin works. Any nickel and other metals of t e same group which may have been contained in the matte ass into the solution, but not on to the cat ode. When a suflicient quantity of they are recovered in accordance with the known processes electrolytes of copper refinin the separation of co per-nicke The technical an commercial advanta es which are achieved by the hereinbeforee scribed manner of working are the following works or for concentrated. copper matte (s urstein) is avoidedthat is to say, electro ytic copper is obtained direct from rich spurstein.

In the methods in use heretofore for.

metallic copper in reverberatory furnaces or converters all air in the form of sulfurous acid. A condensation-of this sulfurous acid into sulfuric acid was not possible, owing to the fact that said sulfurous acid was contained in thefiuegases of the furnace or converter in a too iluted state and was polluted through the resence of other volatile ingredients, instance, arsenic.)

With our process of electrolyzing the matte the entire sulfur remains in the baths as anoderesiduum, from which it-can be recovered other ways.

smelting copper matte for the recovery ofv (for The generation of gases which are diflicultthein has accumulated in the electrolyte,

for treating the impure The operation of smelting crude copper from the sulfur escaped into the 'as solid sulfur by smelting or extraction in to utilize and which have an injurious effect upon the vegetation in'the neighborhood of metallurgica works is also avoided.

at we claim, and desire to secure by Letters Patent, is the following:

The process for the direct electrolytic production of pure copper from copper matte which consists in first bringing the copper matte to a richness of between seventy-two and eighty per cent. of copper, and then using said matte as an anode in an electrolyte composed of an acid solution of copper sulfate.

In testimony that we claim the foregoing as our invention we have signed our names, in presence of two witnesses, this 5th day of September, 1905, respectively, 26th day of August, 1905, respectively, 30th daylof August, 1905.

JOHANNES ALBERT WILHELM BORCHERS. I PAUL RUDOLF FRANKE. FRANZ EMIL GllNTHER. Witnesses to signature of Borchers:

HERLA FROWERK, FERDINAND LANeE. Witnesses to signature of Franke: MARIE SCHNEIDER, EDUARD RICHTER. I Witnesses to signature of Gunther:

' BESSIE F. DUNLAP, LOUIS VANTDORY. 

